Additional Notes

Odds and Ends

Almost all nouns in the fourth declension are masculine instead of feminine. Some exceptions are acus (needle), domus (house), manus (house), tribus (tribe), porticus (colonnade (array of columns)), and Idus (Ides). Trees, by gender rules mentioned in other declensions, also override the noun’s gender as feminine.

In early Latin, ū-stem nouns can take the genitive singular form of -ī.

Only three commonly used neuter nouns exist in the fourth declension: cornu (horn, wing of an army), genu (knee), and veru (spirit).

Artus, tribus, and fourth declension nouns ending in -cus tend to take the dative and ablative plural form of -ubus instead of -ibus.

Some fourth declension nouns can take the dative singular ending -ū instead of -uī.

The Domus Problem

Domus (home) cannot decide whether or not it wants to be in the fourth declension or the second declension. While it is classified as fourth declension (or irregular), the following inflections follow the second declension ŏ-stem pattern: